1. Field of the Invention
The present invention relates to a magnetic-tape library system for accurately mounting a magnetic tape on a magnetic-tape drive by using a hand assembly mounted on an accessor and a method for controlling the positioning of an accessor to the magnetic-tape drive.
2. Description of the Prior Art
A cartridge tape must be accurately transferred from a cartridge-tape storing rack (or cell in a drum unit) to a magnetic-tape drive. By improving the mechanical accuracy of each component unit of a magnetic-tape library system, the possibility of accurate transfer is improved. However, a problem occurs that the cost of the library system is increased.
Therefore, development of a library system capable of accurately transferring a cartridge and making it possible to reduce the manufacturing cost has been attempted so far. For example, the official gazette of Japanese Patent Publication No. 10-69689 discloses a system for accurately transferring a cartridge considering the error between the optical axis of a photosensor for measuring the position of an accessor and the operating axis of a hand assembly provided for the accessor for holing a cartridge in order to correct the error between driving signal of the accessor and the actual driving position.
An accessor is positioned by a photosensor when a laser beam is applied to a marking for positioning from a laser-beam source and the photosensor receives the reflected light of the laser beam. Simple and accurate positioning has been performed so far in accordance with the above configuration. However, the positioning by the photosensor still has a problem.
The problem is described below by referring to FIG. 9. FIG. 9 shows a marking 100 for positioning provided for the front of the above-described magnetic-tape drive. The above-described laser beam is scanned along a read range 114. The marking 100 is located in the read range 114 and constituted of a black area 111 in black and white area 112 in white adjacent along the scanning direction L of the laser beam.
Thus, the boundary line 113 between the black area 111 and the white area 112 is identified when the reflected light of the laser beam changes from black to white through the above scanning. Because the position of the boundary line 113 is recognized, the position of the hand assembly is corrected in accordance with the position of the boundary line 113 and thereby, more precise positioning is performed.
However, the following problems occur in the above case.
First, because the marking 100 shown in FIG. 9 is put on the surface of the frame of the magnetic-tape drive, the circumference of the marking 100 is enclosed by the color of the ground of the frame. When the color of the frame is a color between white and black (e.g. gray), the laser beam reflected before the marking 100 may be recognized as black or white. Therefore, it may be seen as the change from black to white before the marking 100 and a position different from the original boundary line 113 may be erroneously recognized as a boundary.
However, by narrowing the read range 114 of a laser beam (the width of the laser beam in its scanning direction is assumed as X) into the range of the sum of the scanning-directional width A of the black area 111 and the scanning-directional width B of the white area 112 (X less than A+B), it is possible to eliminate the influence of the circumference of the marking. To narrow the read range 114, however, it is necessary to improve the mechanical accuracy of an accessor mechanism and a problem occurs that the cost is resultantly increased.
The invention according to claim 1 comprises a magnetic-tape drive for at least reading data from a magnetic tape, an accessor mechanism for transferring a magnetic tape to and from the magnetic-tape drive, and a controller for controlling operations of the accessor mechanism.
Moreover, the accessor mechanism has a hand assembly for holding a magnetic tape and a predetermined-position detecting section provided for the hand assembly for detecting the predetermined position of the hand assembly to the magnetic-tape drive in accordance with the luminance of the reflected light due to scanning by a laser beam.
Furthermore, the magnetic-tape drive has a marking for positioning to be scanned by the laser beam. The marking is configured by two adjacent areas in black and white each other and these areas are arranged along the scanning direction of the laser beam.
Furthermore, the controller has a start position setting function for setting the scanning start position of the laser beam in a range closer to the marking than the sum of already-known widths of the two areas in their scanning directions before the marking and a positioning function for specifying the boundary between a black area and a white area in accordance with the change of luminances detected by the predetermined-position detecting section and already-known widths of the black area and white area in their scanning directions and positioning the hand assembly in accordance with the boundary position.
Operations will be described below. To position the hand assembly, scanning is performed by a laser beam from this side of the marking. Because the marking has black and white areas adjacent along the scanning direction, a state in which the luminance of the reflected light of the laser beam is low over the width of the black area and a state in which it is high over the width of the white area are continuously detected. Therefore, when the low luminance state is detected for the length equal to the already-known width of the black area and the high-luminance state following the low-luminance state is detected for the length equal to the already-known width of the white area, it is possible to specify the detection of the marking. Moreover, it is possible to specify that a position where luminances are greatly changed is present on the boundary line between the black area and the white area while the detection is performed.
On the other hand, because the area from a scanning start position up to this side of a marking which has been a problem so far is set to a value smaller than the width of the marking in its scanning direction, erroneous recognition of the marking in the this-side area cannot occur by specifying the marking by the above method.
In case of the invention according to claim 2, a controller comprises a memory for storing the already-known width of a black area in its scanning direction and that of a white area in its scanning direction, an area extracting section for extracting a white area and a black area in accordance with a detected luminance, and an area specifying section for specifying a white area and a black area in accordance with the already-known widths of areas stored in the memory.
In case of the invention according to claim 3, an accessor mechanism is characterized by being provided with a position detecting sensor for detecting the relative position relation between a hand assembly and a magnetic-tape drive and moreover, a controller has a roughly positioning section for positioning a hand assembly to a scanning start position in accordance with a relative positional relation for detecting a position detecting sensor.
In case of the invention according to claim 4, a position detecting sensor uses a photosensor.
In case of the invention according to claim 5, a black area is formed of a paint having a low light reflectance.
In case of the invention according to claim 6, at least the range from a scanning start position up to a marking in the area around the marking is made gray.
In case of the invention according to claim 7, areas of a marking are characterized by being arranged in order of a black area and a white area from a scanning start position toward the downstream side of a scanning direction.
In case of the invention according to claim 8, areas of a marking are characterized by being arranged in order of a white area and a black area from a scanning start position toward the downstream side of a scanning direction.
The invention according to claim 9 is provided with a magnetic-tape drive for at least reading data from a magnetic tape, an accessor mechanism for transferring a magnetic tape to and from the magnetic-tape drive, and a controller for controlling operations of the accessor mechanism.
Moreover, the accessor mechanism has a hand assembly for holding a magnetic tape and a predetermined-position detecting section provided for the hand assembly for detecting the predetermined position of the hand assembly to the magnetic-tape drive in accordance with the luminance of reflected light due to scanning by a laser beam.
Furthermore, the magnetic-tape drive has a marking for positioning to be scanned by a laser beam, in which the marking is configured by two adjacent areas in black and white, a black thin area and a white thin area whose scanning-directional widths are set to values smaller than the two adjacent areas, and the white thin area, black thin area, black area, and white area are arranged in order from the upstream side of the scanning directions. Moreover, the distance from the white thin area up to the black thin area is set to a value smaller than the sum of the already-known width of the white area and that of the black area and the distance from the black thin area up to the upstream side of the black area is set to a value smaller than the already-known width of the white area.
Moreover, the controller is provided with a start-position setting function for setting the scanning start position of the laser beam in a range from a position closer to the white thin area than the already-known width of the black area in its scanning direction before the white thin area up to this side of the black area and a positioning function for specifying the boundary between the black area and the white area in accordance with the change of luminances detected by the predetermined-position detecting section and the already-known widths of the black and white areas in their scanning directions and positioning the hand assembly in accordance with the position of the boundary.
To position the hand assembly, scanning by a laser beam is first performed from this side of the white thin area of the marking. The marking has a black area and a white area adjacent along the scanning direction and the black area is located at the upstream side. Therefore, a state in which the luminance of reflected light of the laser beam is low is detected over the width of the black area and then, a state in which that of reflected light of the laser beam is high is detected over the width of the white area. Therefore, when the low luminance state is detected for the length equal to the already-known width of the black area and then, the high luminance state is detected for the length equal to the already-known width of the white area, it is possible to specify the detection of the marking. Moreover, it is possible to specify that a position where luminances are greatly change while detection is performed is present on the boundary line between the black area and the white area.
On the other hand, as for the conventional problem of the area from a scanning start position up to this side of the black area of a marking, the interval from the scanning start position of a laser beam up to a white thin area is set to a value smaller than the already-known width of the black area, the distance from the white thin area up to the black thin area is set to a value smaller than the sum of widths of the already-known width of the white area and that of the black area, and the distance from the black thin area up to the upstream side of the black area is set to a value smaller than the already-known width of the white area.
Therefore, even when the mechanical accuracy of the accessor mechanism is lowered, the distance from the scanning start position up to this side of the black area is set to a large value (the distance is set to a value larger than the sum of widths of the black and white areas), and a luminance change equal to already-known widths of the black and white areas is detected in the above range, each thin area interferes with the luminance change to prevent a luminance change recognized as a marking from occurring. Therefore, erroneous recognition of a marking in this-side area does not occur.
In case of the invention according to claim 10, a controller is characterized by being provided with a memory for storing the already-known width of a black area in its scanning direction and that of a white area in its scanning direction, an area extracting section for extracting a white area and a black area in accordance with a detected luminance, and an area specifying section for specifying a white area and a black area in accordance with the already-known width of each area stored in the memory.
In case of the invention according to claim 11, an accessor mechanism is characterized by being provided with a position detecting sensor for detecting the relative positional relation between a hand assembly and a magnetic-tape drive and a controller has a roughly positioning section for positioning the hand assembly to a scanning start position in accordance with a relative positional relation for detecting the position detecting sensor.
In case of the invention according to claim 12, a range from a scanning start position up to the upstream-side end of a black area is characterized by being made gray except each thin area.
The inventions according to claims 13 to 16 show a case in which the sequence of a white area and a black area for their scanning directions and the sequence of a white thin area and a black thin area are replaced each other.
The invention according to claim 17 is a method for controlling the positioning of an accessor to the magnetic-tape drive of the magnetic-tape library system same as the invention of claim 1 except a controller, comprising:
a before-scanning positioning step of roughly positioning a hand assembly so that the scanning start position of a laser beam is positioned in a range closer to a marking than the sum of already-known widths of areas before a marking;
a scanning step of scanning an object with a laser beam by operating a predetermined-position detecting section and passing through a marking from a scanning start position;
an extracting step of extracting the then scanning range as a black area or a white area in accordance with the level of a luminance detected in accordance with the reflected light of a laser beam;
a specifying step of specifying the extracted black area and white area as a formal black area and a formal white area when the extracted black area and white area are continued and the width of the scanning range of the extracted black area becomes equal to or larger than the already-known width of the black area and that of the scanning range of the extracted white area becomes equal to or larger than the already-known width of the white area; and
a finally positioning step of adjusting the position of the hand assembly in accordance with the boundary line between the specified formal black area and white area.
The invention according to claim 18 is a method for controlling the positioning of an accessor to the magnetic-tape drive of the magnetic-tape library system same as the invention of the above-described claim 9 except a controller, comprising:
a before-scanning positioning step of roughly positioning a hand assembly so that the scanning start position of a laser beam is set in a range from a position closer to a white thin area than the already-known width of a black area in its scanning direction before the white thin area up to this side of the black area;
a scanning step of scanning an object with a laser beam by operating predetermined-position detecting means and passing through a marking from the scanning start position;
an extracting step of extracting the then scanning range as a black area or a white area in accordance with the level of a luminance detected from the reflected light of the laser beam;
a specifying step of specifying the extracted black area and white area as a formal black area and a formal white area when the extracted black and white areas are continued and the width of the scanning range of the extracted black area becomes equal to or larger than the already-known width of the black area and the width of the scanning range of the extracted white area becomes equal to or larger than the already-known width of the white area; and
a finally positioning step of adjusting the position of the hand assembly in accordance with the boundary line between the specified formal black and white areas.
The invention according to claim 19 is a method for controlling the positioning of an accessor to the magnetic-tape drive of the magnetic-tape library system same as the invention of the above-described claim 13 except a controller, characterized by comprising:
a before-scanning positioning step of roughly positioning a hand assembly so that the scanning start position of a laser beam is set in a range from a position closer to a black thin area than the already-known width of a white area in its scanning direction before the black thin area up to this side of the white area;
a scanning step of scanning an object with a laser beam by operating predetermined-position detecting means and passing through a marking from a scanning start position;
an extracting step of extracting the then scanning range as a white area or a black area in accordance with the level of the luminance detected from the reflected light of the laser beam;
a specifying step of specifying the extracted white area and black area as a formal white area and a formal black area when the extracted white and black areas are continued and the width of the scanning range of the extracted white area becomes equal to or larger than the already-known width of the white area and the width of the scanning range of the extracted black area becomes equal to or larger than the already-known width of the black area; and
a finally positioning step of adjusting the position of the hand assembly in accordance with the boundary line between the specified formal white and black areas.
It is an object of the present invention to accurately detect the original boundary between a black area and a white area without being disturbed by an unstable-reflection color other than black or white in the scanning range of a laser beam when detecting the boundary between the black area and the white area of a marking used for positioning.